The present invention relates to an ultra-precise positioning system, by which it is possible to perform the nanometer positioning with high speed and long stroke.
Ultra-precise positioning is one of the basic and important technologies. Particularly, there are strong demands on the ultra-precise nanometer positioning in the fields of semiconductor manufacture, laser optics and optoelectronics machining. Positioning must be performed not only with high precision but also at high speed, whereas high accuracy and high speed are contradictory, and it is not easy to provide both properties at the same time.
To solve these problems, it has been customary in the past to design independent positioning systems for coarse positioning and fine positioning in series, and to provide high speed property by coarse positioning system, while high accuracy is attained by fine positioning system.
The conventional type precise positioning system as shown in FIG. 1 is an apparatus using two-axis moving coil type linear motor 53, and it is applied to air suspension type XY stage for X-ray exposure system. In this system, coarse positioning system is driven by a linear motor 53, and it is stopped by a vacuum locking mechanism 57. Positioning is performed by vacuum locking system to switch over coarse and fine positioning of FIG. 1 (b) and by fine positioning caused by the deformation of XY fine positioning spring 61 as shown in the arrangement of fine positioning spring. The control block is shown in FIG. 2, and FIG. 3 represents the positioning sequence consisting of coarse positioning operation, locking operation and fine positioning operation.
However, the conventional type precision positioning system as described above is complicated in its mechanism and is difficult to be a small size, and the ridigity of the fixing spring by vacuum locking cannot be increased. Accordingly, natural frequency is low and the response cannot be increased. Also, because the positioning sequence is in the order of: coarse positioning.fwdarw.stop.fwdarw.locking.fwdarw.fine positioning. Because much time is required for stop and locking, the positioning time becomes long.